crypto-wallet-address-validator/src/base58.js

Cryptocurrency wallet address validator for Bitcoin, Litecoin and other Altcoins.

// Base58 encoding/decoding
// Originally written by Mike Hearn for BitcoinJ
// Copyright (c) 2011 Google Inc
// Ported to JavaScript by Stefan Thomas
// Merged Buffer refactorings from base58-native by Stephen Pair
// Copyright (c) 2013 BitPay Inc
(function (isNode) {
    var ALPHABET = '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz'
    var ALPHABET_MAP = {}
    for(var i = 0; i < ALPHABET.length; ++i) {
        ALPHABET_MAP[ALPHABET.charAt(i)] = i
    }
    var BASE = ALPHABET.length

    var base58 = {
        decode: function(string) {
            if (string.length === 0) return []

            var i, j, bytes = [0]
            for (i = 0; i < string.length; ++i) {
                var c = string[i]
                if (!(c in ALPHABET_MAP)) throw new Error('Non-base58 character')

                for (j = 0; j < bytes.length; ++j) bytes[j] *= BASE
                bytes[0] += ALPHABET_MAP[c]

                var carry = 0
                for (j = 0; j < bytes.length; ++j) {
                    bytes[j] += carry
                    carry = bytes[j] >> 8
                    bytes[j] &= 0xff
                }

                while (carry) {
                    bytes.push(carry & 0xff)
                    carry >>= 8
                }
            }
            // deal with leading zeros
            for (i = 0; string[i] === '1' && i < string.length - 1; ++i) bytes.push(0)

            return bytes.reverse()
        }
    };

    // export base58 module
    if(isNode) {
        module.exports = base58;
    } else {
        if(typeof window.WAValidator === 'undefined'){
            window.WAValidator = {__imports: {}};
        }
        window.WAValidator.__imports.base58 = base58;
    }
})(typeof module !== 'undefined' && typeof module.exports !== 'undefined');